JPS63313895A - Solder paste printer - Google Patents

Abstract

PURPOSE:To equalize the quantity of printing of solder paste by installing a mechanism keeping the print-separation angle of a printed substrate and a metallic mask constant to a solder paste printer. CONSTITUTION:The angle of a metallic mask 2 and a printed substrate 1, a print-separation angle theta1, and said angle theta2 at the end point B of printing are adjusted previously by a stopper 15 so as to be equalized. When a distance up to a squeegee 4 from a guide pin 13 as the fulcrum of revolution of a plate frame guide 6 at the time of the start of printing is represented by L1, a distance up to a push-up mechanism 14 similarly by L2, the falling pressure, printing pressure, of the squeegee 4 by F1 and the push-up force of a push-up mechanism 14 by F1, printing is started as F1XL1=F2XL2. When the squeegee 4 is moved to the printing end point B side from the state, only the distance L1 changes, F1XL1<F2XL2 holds by the principle of the lever, and the metallic mask 2 is pushed up to the stopper 15 at the end point B of printing. Accordingly, the uniform quantity of solder paste is held.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a solder paste printing machine for printing solder paste on a printed circuit board on which surface-mounted components are mounted, and in particular, it uses a metal mask and a squeegee. In order to print a uniform amount of solder paste on a printed circuit board in a solder paste printing machine that prints solder paste on a printed circuit board by moving, the solder paste is equipped with a mechanism that keeps the plate separation angle between the printed circuit board and metal mask constant at all times. It concerns printing presses.

[Conventional technology]

A solder paste printer using a screen printing method prints by applying solder paste to a printed circuit board through cutouts in a screen.

To explain the outline of the printing mechanism in this type of solder paste printing machine, as shown in Fig. 3, the metal mask 2 of the screen attached to the plate frame 3 is provided with notched holes according to the pattern to be printed. , by moving the squeegee 4,
Solder paste is applied to the printed circuit board 1 through the cutout holes of the metal mask 2 and printed.

In addition, as well-known documents related to solder paste printing machines,
For example, Japanese Patent Application Laid-Open No. 61-238465 can be mentioned.

[Problem that the invention seeks to solve]

In a solder paste printer using a screen printing method, as shown in FIG. 3, a printed circuit board 1 and a plate frame 3 to which a metal mask 2 is pasted are held and fixed at a minute interval. Therefore, with respect to the printing direction, which is the moving direction of the squeegee 4, the printing start point A and the printing end point B are different from each other.
As shown in the figure, the plate separation angle formed by the deflection of the metal mask 2 due to the printing pressure is different at the starting point A and the ending point B, and is θ1. It becomes θ2. The relationship between θ1 and 02 is related to the distance between the metal mask 2 and the printed circuit board l and the moving distance of the squeegee, but θ2 is approximately (1/2) θ1
bawl.

Generally, in a solder paste printing machine that uses this type of screen printing method, the distance between the printed circuit board l and the metal mask 2 is several millimeters or less, and therefore,
As the outer shape of the metal mask 2 becomes larger, the plate separation angle becomes extremely small.

However, it is empirically known that it is better to maintain a small distance between the printed circuit board 1 and the metal mask 2 and to have a large plate separation angle. If this angle is extremely small,
That is, when the metal mask 2 is separated from the metal mask 2 at an angle close to horizontal, the solder paste printed on the printed circuit board 1 is not transferred to the printed circuit board 1 when the plate is separated, and the metal mask A phenomenon occurs in which the object is taken away to the second side. Therefore, as the metal mask becomes larger due to the increase in size and density of printed circuit boards, the plate releasability of the metal mask decreases, resulting in an insufficient amount of solder paste to be supplied to the printed circuit board, resulting in soldering defects. There was a problem that occurred.

The present invention has been made to solve the above problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a solder paste printer equipped with a plate separation mechanism that can always obtain a constant plate separation angle in order to print a uniform amount of solder paste on a printed circuit board.

[Means for solving problems]

In order to achieve the above object, in the present invention, in a solder paste printing machine, a plate frame of a metal mask is supported by a plate frame guide, and the terminal side of the plate frame guide as seen from the printing direction in the squeegee movement direction is used as a fulcrum. The present invention is characterized in that a mechanism is provided that applies upward pressure to the frame guide from below on the starting end side and lifts the starting end side of the frame guide as the squeegee moves.

[Effect]

According to the above means, the plate frame and the metal mask fixed to the plate frame guide are moved toward the starting edge side so that the printed circuit board and the metal mask are parallel to each other at the start of printing, with the terminal end side in the printing direction of the movement of the squeegee serving as a fulcrum. A constant upward pressure is applied from below. As a result, when the squeegee descends, that is, at the start of printing, the printing pressure from the squeegee and the pressure pushing up the metal mask plate frame are equal, so
The metal mask plate frame is parallel to each other, but as it approaches the terminal end, the upward pressure increases due to the lever principle, and the starting edge of the metal mask plate frame is lifted upwards around the fulcrum, so the plate separation angle is always maintained. It can be kept constant.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a perspective view showing a printing mechanism section of a solder paste printer according to an embodiment of the present invention, and FIG. 1 is a detailed explanatory diagram of the plate separation mechanism of the embodiment shown in FIG. In these figures, the same parts as those shown in FIGS. 3 and 4 are designated by the same numbers.

As shown in FIG. 2, the solder paste printing machine according to this embodiment has a printing table 5 that holds and fixes the printed circuit board 1.
A plate frame guide 6 is located above the printing table 5 to hold and fix the plate frame 3 of the metal mask 2, and the plate frame guide 6 is movable parallel to the printed circuit board 1 along a guide rail 8 fixed to a pedestal 7. base unit 9 and base unit 9
a squeegee holder 12 that is movable up and down by a cylinder 10 and a guide holder 11 fixed to the squeegee, and a squeegee made of an elastic material such as silicone rubber that is attached so as to form an acute angle of 90 degrees or less to the printed circuit board 1 with respect to the printing direction. 4 as the main components. Further, a pair of guide pins 13 are provided on the printing direction end side of the plate frame guide 6 and protrude from the pedestal 7, and the guide pins 13 are inserted into the plate frame guide 6 and serve as a rotational fulcrum of the plate frame guide 6.

A push-up mechanism 14 is provided below the starting end side of the frame guide 6 in the printing direction, and is operable in synchronization with the movement signal of the squeegee 4, and is made of an air cylinder or the like with adjustable push-up pressure. ing. Furthermore, a stopper 15 for stopping the plate frame guide 6 at a required stroke is provided above the push-up mechanism 14 across the plate frame guide 6, thereby forming a plate separating mechanism.

The printing operation of the solder paste printer having such a configuration will be explained with reference to FIG.

Usually, the printed circuit board 1 and the metal mask 2 are set parallel to each other with a very small distance of several millimeters or less. Also in the configuration of the solder paste printing machine of this embodiment, the printed circuit board 1 and the metal mask 2 are parallel to each other at the start of printing, and the metal mask 2 and the printed circuit board 1 are formed by lowering the squeegee 4 at the printing starting point A. This angle is adjusted by the stopper 15 so that the plate separation angle θ1 and the same angle θ2 at the printing end point B are the same. Further, the distance from the guide pin 13, which is the rotational fulcrum of the plate frame guide 6 at the start of printing, to the squeegee 4 is I, 1 - Similarly, the distance to the push-up mechanism 14 is L2. When the downward pressure of the squeegee 4, that is, the printing pressure, is Fl, and the push-up force of the push-up mechanism 14 is F2, Fs XLz = F
2 Start printing as XLz. When the squeegee 4 is moved from this state to the print end point B side, only Ll changes, and due to the lever principle, Fu XLt < F
2 XLz, the metal mask 2 is gradually pushed upward by the push-up mechanism 14 together with the plate frame 3 and plate frame guide 6, and when reaching the printing end point B, the metal mask 2 is pushed upward by the stopper 15.
be pushed up to. Here, the relationship θ1=02 is maintained. In this embodiment, the power source of the push-up mechanism 14 is a cylinder, but a cam may be used to perform the same operation).

Therefore, according to the plate separation mechanism of this paste printing machine, the plate separation angle between the printed circuit board and the metal mask during printing is always constant, and the plate separation between the metal mask and the solder paste can be set within the best range, so that it is uniform. It is possible to hold a large amount of solder paste. In addition, since the solder paste is less likely to be carried away by the metal mask side, printing can be performed continuously, improving work efficiency and reducing costs.

Although the present invention has been specifically described above based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the invention.

〔Effect of the invention〕

As described above, according to the present invention, the solder paste printing machine is provided with a mechanism that makes the plate separation angle between the printed circuit board and the metal mask constant, so that it is possible to easily make the printed amount of solder paste uniform. This has the effect of significantly improving soldering quality and providing highly reliable soldered connections.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram illustrating a plate separation mechanism according to an embodiment of the present invention, FIG. 2 is an external perspective view showing the printing mechanism section of a solder paste printer according to an embodiment of the present invention, and FIG. 3 is a conventional FIG. 4 is an explanatory diagram showing the printing state of the solder paste in FIG. 3 in detail. In the figure, 1... printed circuit board, 2... metal mask,
3... Print frame, 4... Squeegee, 5... Printing table, 6... Print frame guide, 7... Mount, 8... Guide rail, 9... Base unit, 10... ... Cylinder, 11 ... Guide rod, 12 ... Squeegee holder, 13 ... Guide pin, 14 ... Push-up mechanism, 1
5... It is a stopper.

Claims (1)

[Claims] 1. In a solder paste printing machine that uses a metal mask and prints solder paste on a printed circuit board by moving a squeegee, the metal mask plate frame is supported by a plate frame guide,
Using the end side of the plate frame guide as seen from the printing direction in the squeegee movement direction as a fulcrum, upward pressure is applied to the plate frame guide from below on the starting end side, and as the squeegee moves, the starting end side of the plate frame guide A solder paste printing machine characterized by having a mechanism for lifting the solder paste.